Extend Lines Using the CAD Command Line

Use the Extend command alias on the CAD Command Line to lengthen selected lines to their planimetric intersection with a specified bounding line (shown in green) or by a specified distance.

Extending lines to their intended intersections or lengths can help you clean up error-prone data, resulting in better surface formation and more accurate volume calculations. Lines can also be extended even when they do not intersect a bounding line; they can be extended to the intersection point of a projection of the bounding line.

Lines are extended as shown.

	Bounding lines
	Lines to extend
	Extension
	Point picked; lines extend the target lines to nearest boundaries, click again to extend to the next bounding line.

You can select lines to extend by picking them or by 'windowing' around them.

	Bounding lines
	Lines to extend
	Extension
	Selection window (rectangular selection)

Prerequisites:

License; See the Subscription Plans page. For a license matrix by command, see the License page in the TBC Community. Also see View and manage licensed features.
Lines to extend
Optionally, lines to limit the extend operation (boundary lines)

To extend one or more lines to a bounding line or by a distance:

Press [F3] or click the icon on the Status Bar to open the CAD Command Line near the bottom of the screen.
Type ex or EX at the command prompt, and press [Enter].
Skip the Layer, Color, and Line style lists below the command prompt; they do not apply to this operation.
Based on the highlighted Bounding line mode (in orange), pick a 'bounding line' to extend one or more lines to in a supported graphic view (Plan, 3D, or Cutting Plane) and press [Enter], or type a keyword character to use another mode. The options are:
- Bounding Line - Enter B, pick a bounding line. Pick additional bounding lines or press [Enter] to complete the selection of bounding lines.
- Distance - Enter D, specify a length to extend the lines by and press [Enter], or pick two points to specify the distance.
The command remembers the last modes used the next time you run the command.
In the view, pick the line you want to extend. Pick additional lines to extend to the selected bounding line as needed. You can also 'window' around multiple lines that you want to extend.
Note: Polygon selection cannot be used to select bounding lines and target lines; the program cannot determine which parts of the lines were selected. If the current selection mode is polygonal, the command changes the mode to rectangular section, and changes back to the polygon selection when the command finishes.
To trim a line using the bounding line instead, press [Control] when you pick the line.
Press [Escape] to end the command and return to a blank command prompt.
Press [Spacebar] to rerun the command.